This invention relates to the field of hand-operated lever controls and, particularly, to an improved control design employing a spring-tensioned pivoting eccentric assembly linked to the pivoting lever to provide a mechanical advantage during actuation of the control function.
Hand-operated lever assemblies for actuation of various control functions are well known in the art. These assemblies are common to a great number of motorized and other apparata, such as multiple-speed bicycles, motorized snow sleds, various gas-powered tools, bulldozers and other earth-moving equipment and all varieties of motorcycles.
Common to all such lever controls is the presence of a housing or other means of attaching the control to the particular vehicle and a lever arm pivotally mounted to this housing. Common also is the principle of connecting a cable, mechanical or hydraulic linkage control for a brake, clutch or other function to this pivoting lever with the lever travel then corresponding to the engagement or disengagement of the particular control function. For the remaining purposes of this specification, reference will be specifically made only to a cable-operated control in connection with the present invention. It is understood, however, that the invention has equal application to and provides equal advantage with lever controls employing mechanical, hydraulic or other linkage operably connected to a particular control function.
The lever travel necessary to operate the control function requires in all cases a certain amount of force to actuate the control cable or other linkage. Understandably, the magnitude of force required to engage or disengage this control function varies greatly, depending upon many factors including the particular lever design and the equipment in use. But regardless, some force is required in all such cases; and the physical energy required to provide this force and to operate the particular control can be appreciable as, for example, in the case of the repeated operation of a clutch lever control on a motorcycle, bulldozer or other heavy equipment.
Certain devices are also known in the art for achieving a mechanical advantage to assist in the performance of a specific task. For example, eccentric arrangements involving rods, discs and other members not coaxial in design are commonly used in a variety of circumstances, such as the cam shaft in a motor vehicle and the stringing assembly in a compound bow. Springs are also commonly used devices in this regard, as in the spring-loaded power transmission system disclosed in Richmond, U.S. Pat. No. 3,599,508.
Attempts have also been made to incorporate such devices for achieving a mechanical advantage into the designs for hand-operated lever controls. For example, Sorenson et al., U.S. Pat. No. 3,903,679, discloses spring means 42 and 42' mounted on the frame of a lawn mower for urging a specific bracket 36 and 36' into the clutch-disengaging position to assist in operating the lawn mower. Camp, U.S. Pat. No. 3,845,847, on the other hand, discloses in FIG. 3 the use of a spring 34' to provide an urging force to pull the cable 26 and urge the lever 24 away from the grip to thereby engage the brake and cut-off switch.
Regardless of these prior art attempts, however, the need exists for a compact and practical hand-operated lever control that is adaptable to a great variety of uses and that includes some means for simply and efficiently providing a mechanical advantage to assist in lever travel and in actuation of the control linkage.